A pressure chamber scraper of this kind is known, for example, from DE 299 17 979.6 U1. This document describes that the displacement element is lowered into a recess of the chamber and is screwed to the scraper head. Setscrews are provided for changing the distance between the displacement element and the drum. In the known pressure chamber scraper the medium to be applied is introduced into the pressure compartment through lateral openings in the displacement element, so that a homogeneous distribution of the medium across the axial length of the pressure compartment and thus in the application gap will result. However, a pressure compartment of this kind is relatively difficult to clean when changing the application medium or in case of an interruption in operation. In particular, a partially tacky and highly viscous medium settles onto the threads of the screw connections and hardens there, and it can only be removed with much difficulty or only with the use of aggressive solvents. Also, the openings can quickly plug up.
It turns out that in the case of these pressure chamber scrapers a particularly homogeneous distribution of the medium in the application gap and a targeted volume dosing are dependent in particular on the size of the openings in the displacement element. Tight openings with a high throttle effect are particularly useful, so that when working with only one or up to three openings, the medium can be supplied uniformly into the pressure compartment and to the application gap. However, the manufacture of these tight openings in the displacement element is subject to certain limitations. Firstly, a longitudinal slit with a slit dimension of less than 2 mm cannot be manufactured in an economical manner. And secondly, this kind of narrow opening cannot be cleaned when necessary.